The invention relates to abrasive compositions suitable for medical and cosmetic purposes such as the treatment of acne, and for technical applications, e.g. as polishing materials for delicate surfaces.
Abrasive compositions conventionally comprise an abrasive or scouring component that may be combined with a variety of carriers,adjuvants and active substances, depending on the intended use. Some fields of application call for abrasive compositions which are adjustable as to their abrasive or scouring action. Of particular interest are compositions showing a gradual, controlled decline of abrasive or scouring action during use.
The above problem is encountered, for instance, in cosmetic preparations for the treatment of acne. If conventional abrasives such as sand, silicates, silica gels or aluminum oxide are added to such preparations, the constant scouring action, particularly with excessive use of the preparation, would cause irritations and damage to the skin. For this reason, cosmetic preparations usually comprise sodium tetraborate (borax) as an abrasive in a conventional soap base. Sodium tetraborate has the advantage of a hardness suitable to the intended purpose while its scouring action gradually diminishes through the abrasion effected, thus preventing any damage to the skin. Recently, however, it has been discovered that boron compounds may be detrimental to the health of the user and as a result, e.g. boric ointments have practically all been taken from the market.
Also known is the use of sodium chloride as an abrasive in cosmetic preparations of the above described type. These abrasives do, however, cause skin irritations, and painful smarting of the skin, particularly with minor injuries, is frequently observed.
Surprisingly, it has now been found that porous organo-modified silicic acid heteropolycondensates provide excellent abrasives, as their abrasive or scouring action, both absolute and as a function of time, is adjustable in a defined manner.
Because of these characteristics, the abrasives of the invention are suitable not only for medical or cosmetic preparations such as acne treating compositions or tooth pastes, but for technical and industrial applications as well, e.g. in cleansing and polishing materials for paint coatings, enamels or other delicate surfaces.